There is known a device for training ball strikes, comprising an elastic belt with attachment elements. The belt has a carbine and a slide for engagement with an immovable support (see U.S. Pat. No. 4,325,548, IPC A63B69/00, published 20 Apr. 1982). However, the device has a long period of after-hit swings, and also does not allow the volleyball players to control correctness of operation of the player's hand.
There is known a device for training strike movements, comprising a slide incorporated in a casing, a springed pressing plate for contacting with the slide situated in a longitudinal slot of the casing and furnished with a mechanism regulating the pressure force and mounted outside the casing, an element for reverse of the pressing plate into the initial position, a rod, an elastic element situated around the rod, the rod having limit holes for fixing a predetermined length of the elastic element; the casing is so designed that is capable of displacing along the axis of the rod, the plate is so designed that is capable of turning in the longitudinal slot of the casing and reciprocal-progressive movement along the axis, perpendicularly to the axis of the casing; the device is distinct in relation to known devices in that it is furnished with a unit for reverse of the rod into the initial position, which unit is joined with a flexible puller having a first end of the rod and a second end thereof, wherein the second rod is joined with a carbine via a flexible puller, the contact portion of the pressing plate is made in a rounded shape to provide a pointed engagement surface with the slide, the slide is designed as a sphere with an inner hole for the rod and providing fixation of the sphere on the rod, having a fixing element in the initial position, wherein the casing is made immovable. The aforesaid device for training the striking motions is supplied with an imitator of a sporting implement for indication of the place of strike with a possibility of its return into the initial position (see Russian Federation Patent No. 2224565, IPC A63B69/00).
However, the reciprocal-progressive mechanism of the above-mentioned device provides a movement of the ball along the straight line, whereas the player's hand is moving along an arc. During the striking movement of the palm part of the hand at the ball, the ball and the hand are being in contact at a distance of 25-35 cm. This period is called “co-striking”. Different trajectories of the ball and the hand lead to non-correspondence of the bio-mechanical conditions of the “co-striking” that is reflected in the quality of training. Also, the aforementioned device is insufficiently effective for practicing the strike techniques because of the limitations of degree of free movement, which limitations cause high demands to precision of the strike motion performance. This is unacceptable for training novice sportsmen, who have not acquired a movement reflex of striking motion.
The most close to the proposed solution is a device for training of tennis players, including a support with a bracket with a horizontal axis secured thereon and having a clamp. A bracket-shaped frame is disposed therein, supplied with elastic stretch elements with a ball secured thereon. The bracket is mounted on a pole, the frame is mounted on the axis at a predetermined angle to the horizon. The elastic stretch elements provide the role of a reverse mechanism (USSR inventor certificate 641973). The mentioned device can be utilized for training volleyball sportsmen when a volleyball ball is used rather than the tennis ball.
However, after a strike, the ball is moving reciprocal-progressively, whereas the hand is moving along an arc, that leads to inconsistency of movement trajectories at the “co-striking”. This creates discomfort, can lead to a trauma, and does not allow appropriate improving the strike technique. Following the strike, the ball returns into the initial position only after long chaotic oscillations. Besides, a shortcoming of the device is absence of immediate feedback information about the quality of the strike performed.